(CNN) --Coalition forces took control of the strategic Faw Peninsula Friday, according to Lt. Col. Rick Long, spokesman for the 1st Marine Expeditionary Force. The peninsula includes key oil installations, as well as the port city of Umm Qasr, Iraq's only outlet to the Persian Gulf. The old port was taken by British troops; U.S. Marines seized the new port.

CNN's Christiane Amanpour spoke with British military spokesman Chris Vernon while that battle was underway. She joined CNN anchor Bill Hemmer with this report.

HEMMER: One thing we learned today is about military jurisdiction between the U.S. and British forces and how they will divvy up jurisdiction and responsibility inside Iraq. We now know that the British will largely be responsible at some point soon for southeastern Iraq. This includes that port city [Umm Qasr] that sits on the Persian Gulf.

CNN's Christiane Amanpour reported this news first. She is with the British Marines now and joins us with more. Christiane -- hello.

AMANPOUR: Bill, indeed, the British are eventually going to have control and responsibility for this part of southern Iraq. Once they get Umm Qasr, they will have control of those key strategic and economic targets.

Now they have been working with the Americans, sometimes in joint operations, sometimes in separate but simultaneous ones. The U.S. forces, Marines, launched last night into the Rumaylah oil fields, which they're trying to secure and control. The British have taken the Al-Faw peninsula, the UK Royal Marines. The Al-Faw peninsula, which is part of the oil terminal, [is] a very important strategic and economic target.

And now, the U.S. Marines, American Marines, along with some British commandos, are battling for Umm Qasr, which is Iraq's big commercial port. There have also been prisoners taken, some 250 prisoners taken by U.S. Marines and about 30 or so by the UK Marines.

We're going to turn now to Colonel Chris Vernon, who is the spokesman, the military spokesman, for these coalition forces here.

Tell us what is the latest on the Umm Qasr, the battle for that big commercial port there.

COL. CHRIS VERNON, BRITISH MILITARY SPOKESMAN: Clearly there's quite a fight going on, and therefore it's a little bit unclear. But they have taken prisoners, as you said.

AMANPOUR: Now, were you -- were they surprised by the resistance since they had more -- you know, less resistance than some of the other places they went to?

VERNON: No, I don't think so. The British commando raid onto the Al-Faw peninsula last night, [which] we knew was far more sparsely populated and militarily far less inhabited than the Umm Qasr port, which is a bigger metropolis of around 4,000 people.

AMANPOUR: And let's talk, because we've been reporting this U.S. helicopter that went down with both U.S. and British troops. Tell us exactly where that went down.

VERNON: It was involved within the Al-Faw operation. I haven't got the exact location of where it went down. An American helicopter transporting in British Marine commandos sadly went down, and there were the four American crew and eight British commandos on board [who] were killed.

AMANPOUR: And that was inside Iraq, you are saying?

VERNON: It was probably over Iraqi airspace, yes.

AMANPOUR: What is the strategic significance, and what will the British forces be doing once these targets are taken, in the south?

VERNON: Critically, one of the main issues is the oil infrastructure. Al-Faw has the terminals, as you've just described it. But further to the inland south of Rumaylah are the five gas and oil separation plants. These are the areas to which the oil wells feed, and the criticality of them is, if destroyed, it would take a very long time to regenerate and rebuild. Thereby, if there was that gap, Iraq would not be able to produce oil for its economic prosperity in the future.

AMANPOUR: So you're trying to make sure that they're not disrupted and they're not burned. But there are a few wells burning. We've had confirmation of that both from the British defense secretary and officials in Washington.

VERNON: That's correct, but a few wells is not the issue. The main point is the gas and oil separation plants are broadly intact.

The other thing about this is if we can get them intact, flash these sorts of messages through up into Baghdad, we can almost get the message, 'Here is your future economic prosperity, think very, very closely now about whether you wish to retain this regime in power.'

AMANPOUR: And about Basra, the important population center in the south. Are you aiming to get that? Is that a target?

VERNON: It doesn't represent a direct military target, because as we see it at the moment, there are no Iraqi military forces around it. Once we have made the area benign, thereby eliminated Iraqi forces, or the better option, they have capitulated to us, and we've been saying that's what we would welcome, then we will look at Basra. But we will not enter it until we think we are broadly welcomed in there.

AMANPOUR: Colonel Vernon, thank you very much indeed. So that's the latest from this southern part, or the southern part of Iraq. We're right now in northern Kuwait at the divisional headquarters of the field forces here, the British field forces. And they are waiting, as I say, to have Umm Qasr, that important commercial port in their hands so that they can bring up all of the humanitarian aid and the food and all sorts of other relief supplies that they'll need for the population as this wears on.

Back to you -- Bill.

HEMMER: Christiane, thanks -- Christiane Amanpour in northern Kuwait with the British Marines.